Do we want Flutter to be run on top of 802.15.4 PWAN? It would be a potential point for interoperability and allow for us to use 6LoWPAN to transfer IPv6 packets on top of it. On the other hand, it may be over-complicated for what we want to start with.

Well, the chipset supports 802.15.4 in hardware, but for maximum range we are doing narrowband RF with frequency hopping, which isn't compatible with 802.15.4. You can get a couple hundred meters with Flutter in 802.15.4 mode and the chipset can switch on the fly, so it could be possible to do both.

I'd also love to see Flutter interface with the $15 GE Wink LED bulbs, since the factory hub is awful. Those are Zigbee or Z-wave (which I think is Zigbee? forgetting...).

Zigbee is a bastardized proprietary version of 802.15.4, and if I remember correctly, isn't compatible with anything but itself. It also requires a license to implement, so unfortunately it's not something that I think we can do - unless some poor sucker here wants to attempt a clean room reverse engineering for interoperability.